Regional system of radio broadcast distribution



April 15, 1930. E. 'E. CLEMENT Y 1,754,876

REGION AL SYSTEM OF RADIO BROADCAST DISTRIBUTION Filed Feb. 9, 1924 3 Sheets-Sheet l April 15, 1930. E. ECLEMENT 1,754,876

REGIONAL SYSTEM OF RADIO BROADCAST DISTRIBUTION I nsane/0 l I. LIE/IT ml 1 news/e April 15, 1930. CLEMENT 1,754,876

REGIONAL SYSTEM OF RADIO BROADCAST DISTRIBUTION Filed Feb. 9, 1924 3 Sheets-Sheet 3 Patented Apr. 15, 1930 UNITED STATES PATENT OFFICE EDWARD E. CLEMENT, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR TO EDWARD F. COLLADAY, OF WASHINGTON, DISTRICT OF COLUMBIA REGIONAL SYSTEM OF RADIO BROADCAST DISTRIBUTION n Application filed February 9, 1924. Serial No. 691,824.

My invention relates to regional systems of distribution for radio broadcasting from a central station to subscribers stations, and has for its object the production of a system in which secrecy may be maintained and improved reception of all stations assured. According to my invention, heterodyning is employed to secure improved receiving at substations as well as secrecy, and electric light 0 wires or the equivalent are employed for conveying the modulated waves to said substations, heterodyning waves being transmitted through the ether, or vice versa at will and interchangeably. My present invention is an improvement in the respect stated over inventions disclosed and claimed in my prior copending applications Serial No. 581,829, filed August 14, 1922, patented January 6, 1925, No. 1,522,357, and 667,024, filed October 6, 1923, patented March 9, 1926, No. 1,576,309. In respect to part of the subject matter, this application is' a continuation in part of my application No. 667,024, and it is also related as a continuation in part to my prior applica- 2 tion Serial No. 586,842, filed September 8,

1922, patented December 11, 1928, No. 1,695,- 171, jointly with James B. Hoge.

My invention is illustrated in the accompanying drawings, in which:

Fig. 1 is a diagram showing a combined electric light and radiophone system embodying my invention.

Fig. 2 is a diagram showing the connections at the central station and a subscribers station.

Fig. 3 is a diagram showing the circuits at a subscribers station, together with telephone connections to a central office, a portion of an electric light network, and a meter of convenient type.

Fig. 4 is a diagram showing a connection of the meter for registering time use.

Referring to the drawings, and particularly to Fig. 1 this shows an electric ligJ ting system with a central power station five transformer substations, C, C C C C, consumers mains M fed from the substations, and feeder mains M, distributing the power from the main generating plant typi- 50 fied by G to the substations. At the central station Sw indicates the usual main switchboard, and Sw a supplemental switchboard for purposes to be described. From this board Sw communication wires 35, 37, 39, 41 extend out to the substations, one pair or more accompanying each feeder cable in the ducts. At each substation a small switchboard Sw is provided, equipped with an automatic selective switch 36, 38, 40 or 42, having a switch arm or wipers connected to the in coming line 35, 37, 39 or 41, and contacts over which the wipers arestepped in operation, to connect with local lines to consumers radiophone stations. Thus at substation C the switch 36 has contacts connected to wires 43, 44, which extend from that substation to the radiophone stations 43", 44. This same substation C carries a feeder main M to a second transformer station C and the accompanying communication wire 45 extends to a switch 46 at said substation, from which wires 47, 48 extend to radiophone stations 47*, 48*. This subdivision of the system requires an extra digit in the number transmitted from the central stationC, the switches 34, 36, and 46 corresponding to first and second selectors and connectors in an automatic telephone system. No detail of the switching circuits or the operating mechanism of the automatic switches is given herein, as such circuits and switches are well known, and of themselves form no part of the present invention, the main features of which as regards the communication circuits, lies in the ability of the central oflice operator to automatically connect himself to any part of the system through the minimum number of wires, comprising in this case a single pair from the central station to each substation, and single pairs diverging therefrom to the further subdivisions of the system. The last link in any of these circuits is the individual drop wire, extending from a terminal box to the building in which current is to be used. These drop wires are relatively short, and I contemplate employing them for a double purpose, viz., for communication by phone or ot erwise over the wires, and as antennas for the radiophone instruments, where found expedient or desirable. This will be described hereinafter.

through 60-60 .local oscillator 00 in place of the relay trans- 'lransformers K are the substation transformers, and transformer K? are the house or pole transformers feeding the consum tion circuit M from the house mains The consumption circuits M lating devices such as lamps L, and may also supply current to the radio telephone receivers RR, to be presently described. These radio telephones are all standardized and of uniform design and construction, and are calibrated and locked when installed, so as to operate on a common wave length only, i. e., the beat Wave length due to heterodyning-of Waves of different frequencies received over the circuit M and through the ether, respectively. A transmitter RT may be located at the central power station or at some other point on the central power distributin sy tem, and in any case, the switchboar S'w will be located at the same point, and distribution over the communication circuits effected therefrom. Since the local radio telephone receivers RR are all uniform and fixed as to their tuning, any tuning required must be on the part of. the transmitting operator at switchboard S'w, who is able to listen in and observe the operation of the outlying receiving instruments.

For supervision of the quality of reception, testing, etc., of a subscribers radio receiver, and controlling the quality of reception, the operator at the central station 0 makes use of the telephone connections to be established through the automatic switching means and circuit connections indicated in Fig. 1 at 32, 34, 35, 36, and 43-44. or example, if the receiving set at sub-station 48 is to be connected with, the operator at the central station first operates his dial 32 to step the switch 34 around into connection with line 35 leading to sub-central C, then dials again to extend the connection through switch 36 to line 45 leading to sub-central C and again operates his dial 32 to step the switch46 around into connection with line 48, the indi- Throu h the vidual drop lineto station 48*. connection thus established the centra station operator is enabled to listen'in on the audio reproduction of the subscribers receiver, which observation will enable him to determine what faults are present and the necessary remedies to be applied. I

Referring to Fig. 2, the transmitting and receiving connections are shown in more detailthan in Fig. 1 wherein relay radio transmitter= RT is normally connected through suitable switch 60-60 and coupler CC to the main distribution circuits M, preferably the switchboard Sw. The switch can be thrown soas to connect the lnitter RT. The second local oscillator 00 is used to radiate heterodyning waves to the substation receiver RR to balance against the wire guided waves from the transmitter adapted to RT or the equivalent local oscillator 00. When the relay transmitter RT is receiving and distributing to the local subscriber, modulated waves from distant stations, the modcarry trans-' ulated waves are confined to the wires and the heterodyning waves from 00 can be unmodulated, which renders them imperceptible to any but subscribers. When the local oscillator 0C is connected to the network in place of RT, since both com onent wave trains are locall originated at 8C. and 00' respectively, either one can carry the modulations, hence I have shown the local'modulator LM adapted to be connected by switches 6161 and 62-62F'with either one of the 10- cal oscillator circuits at will and interchangeabl Iii Fig. 2, RT represents the relay transmitter for distributing waves from distant stations, it being understood that they are amplified toany desired degree in passingthrough the relay transmitter RT. The symbols in Fig. 2 marked RT represent therefore a complete receiving, transmitting device, adapted to take modulated waves from distant stations and transmit them over the net work MM SC is the subscribers coupler to his antenna SA, RR is his instrument as a whole, the ing phone being shown at r. At the central station in Fig. 2, the coupler CC can be connected to the local oscillator 00 while the companion oscillator 00' is connected through a coupling 00 to the aerial radiator OA.

In Fig. 3, the subscribers station is further amplified. The coupler 28 and antenna 25 are the same as in'Fig. 2, but the connection from house mains M through a plug P from which conductors are led to the heterodyning coupler coil which amplifying, and

receivis brought in is shown inserted in the filament grid circuit I of the detector tube. Since heterodyning is equivalent in its effect to one stage of audio amplification, and since radio amplification takes place at the central station C, I show one stage of audio amplification at the subscribers station, and a loud speaker; but this is understood to be typical only, and head telephones may be used or any known or-suitable arrangement of heterodyning circuits may be substituted the circuit shown.

The meter shown in Fig. 3 is not claimed herein but consists of-a Veeder counter or the equivalent with an actuating magnet be energized each time the set is put into operation. Instead of this arrangement of meter for registering the number of times the set is used, time ofuse may be registered if desired by substituting any known or suitable form of meter therefore, as for example that shown in Fig. 4, and in my prior application Serial No. 586,842 (Patent 1,695,171) hereinbefore referred to.

for the audio portion of consumption,

I claim:

1. In a regional distribution system for radio broadcast, a central station, a wired network extending therefrom to outlying points of consumption, and connected to all of said points in common, subscribers radio telephone receiving instruments at said points of means at the central station for transmitting radio frequency waves over said wired network, other means at the same central station to radiate radio frequency waves throu h the ether, means at the central station or controlling the frequency relation between the two sets of waves such as to produce a given superaudio beat between them when combined, means at each subscribers station to receive both of said sets of waves,

one over the wired network and the other.

through the ether, with means to heterodyne the same and to detect and reproduce the signal modulations in the subscribers receiving instrument, said receiving heterodyning and detecting means being permanently tuned to a fixed and predetermined frequency calibrated and locked, whereby no tuning is required to be done by the subscriber.

2. In a regional distribution system for radio broadcast, a central station, a wired network extending therefrom to outlying points of consumption, and connected to all of said points in common, subscribers radio telephone receiving instruments at said points of consumption, means at the central station for transmitting radio frequency waves over said wired network, other means to radiate radio frequency waves through the ether, the frequency relation between the two sets of waves being such as to produce a superaudio beat between them, means for modulating one of said sets of waves, means at each subscribers station to receive both of said sets of waves, one over the wired network and the other through the ether, with means to heterodyne the same through suitable detecting means so as to produce in a telephone receiver audio waves corresponding to the said modulations, said heterodyning means and the detector circuit being permanentl tuned, calibrated and locked.

3. n a regional distribution system for radio broadcast, a central station, a wired network extending therefrom to outlying points of consumption, and connected to all of said points in common, subscribers radio telephone receiving instruments at said points of consumption, means at the central station for transmitting radio frequency waves over said wired network, other means at central to radiate high frequency waves through the ether, the frequency relation between the two sets of waves being such as to produce a superaudio beat between them, means at each subscribers station to receive both of said sets of waves, one over the wired network and the other through the ether, with means to heterodyne the same through suitable detecting means so as to produce audio waves in a telephone receiver, said heterodyning and etector apparatus being tuned, calibrated and locked together with means at the central station for modulating one of said sets of waves, and means to apply the modulator to either one of the waves transmitters, at will.

4. In a system of radio broadcast distribution, a central station and subscribers stations, a wired network interconnecting them, said network being common to all for the general distribution of electric currents, means at the central station for radiating modulated wavesthrough the ether, means also at the central station for transmitting unmodulated waves through the wired net work at a diiferent frequency from the ether waves, means at the subscribers stations for receiving through the ether and over the network respectively said two sets of waves, and for combining or heterodyning the same so as to produce a modulated and detectible beat waves, said means being permanently tuned, calibrated and locked against disturbance, gether with means under control of the central station operator for reversing the mode of transmission of the respective wave trains, so as to radiate the unmodulated waves, and to transmit over the wired network the modulated waves, and other means under control of the central station for maintainingv a constant difference in frequency between the two wave trains.

In testimony whereof I hereunto aflix my signature.

EDWARD E. CLEMENT.

Elli 

